Two-Node Cluster With Two Logical Hosts, Application Servers, and Separate NFS Cluster

A two-node cluster with two logical hosts can be configured with SAP application servers on one or both physical hosts. In this configuration, you must provide NFS services from a host outside the cluster. Set up the application servers to NFS-mount the file systems from the external NFS cluster, as illustrated in Figure 10-5. In this case, both nodes are utilized and load-balanced.

In case of failover, the logical hosts switch over to the sibling node. The application servers do not fail over.

If the central instance logical host fails over, the application server can be shut down through the hasap_stop_all_instances script.

There are no customizable scripts to start and stop application servers in case of failover of the database logical host. If the database logical host fails over, the application servers cannot be shut down to release resources for the database logical host. Therefore, you must size your configuration to allow for the possible scenario in which the central instance, database instance, and application server are all running on the same node simultaneously.

In this configuration, NFS is protected by Sun Cluster HA for NFS. For more information, see "Sun Cluster HA for NFS Considerations".

Figure 10-5 Symmetric SAP Configuration With Two Logical Hosts and Application Servers